Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world with poor prognosis. Here, we investigated the role of microRNA 218 (miR-218) in regulating human HCC development. Quantitative PCR (qPCR) was used to compare the expression levels of miR-218 between eight HCC and a normal liver cell lines, as well as nine primary HCC tissues and adjacent non-carcinoma tissues. HCC cell lines MHCC97L and Huh7 were transfected with lentiviral vector of miR-218 mimics. The effect of miR-218 overexpression on cancer cell growth, both in vitro and in vivo, as well as cancer cell invasion was examined. A bioinformatic method was used to predict the binding of miR-218 to RET proto-oncogene (RET). Small interfering RNA (SiRNA)-mediated genetic knock-down of RET was performed in MHCC97L and Huh7 cells, and its modulatory effect on miR-218-mediated HCC development was examined. miR-218 was found to be downregulated in HCC cell lines and primary HCC tissues. Overexpression of miR-218 in MHCC97L or Huh7 cells resulted in significant decrease in cell proliferation and invasion capability. Overexpression of miR-218 also reduced the tumor growth of xenografted Huh7 cells in vivo. The expression of endogenous RET was found to be upregulated by miR-218, and siRNA-induced RET downregulation resulted in phosphatase and tensin homolog deleted on chromosome 10 (PTEN) upregulation and reversal of the inhibitory effect of miR-218 upregulation on HCC proliferation. Our results indicate that miR-218 modulates HCC development, and this effect may be through RET and PTEN.